The necessity for the aeration of aquarium water in order to sustain marine life as well as the removal of impurities and waste products, and undesirable accumulation of solid matter is a problem which has existed for some time. Attempts have been made to solve this problem by circulating the water through suitable filters, usually external to the aquarium, and then subsequently cleaning or replacing the filter media used. Aeration or the supply of sufficient oxygen has been treated as a separate problem and various methods have been devised for producing this in an aquarium. The prior patent art as known to the applicant at this time is summarized briefly below.
Eheim, U.S. Pat. No. 3,489,095 discloses an electric pump and motor in combination with a fish tank and filter which represents the old method of solving this problem.
Willinger, U.S. Pat. No. 3,512,646 is another pump and filter combination and in this case magnetically coupled for circulating aquarium water through an external filter.
Zelanko, U.S. Pat. No. 3,643,801 teaches a novel disposable filter element positioned in a separate compartment for easy replacement.
Cohen, et al, U.S. Pat. No. 3,994,811 teaches an air operated device which skims and filters water by-passed from the aquarium and then returns the clean water to the aquarium.
Sherman, U.S. Pat. No. 4,093,547 discloses a pump positioned or nested against an aquarium tank which circulates water by means of a magnetically coupled pump and returns it to the filter.
Gorsky, U.S. Pat. No. 4,163,035 discloses a specifically constructed aeration device located exterior to the aquarium.
The patents of Kast, U.S. Pat. No. 3,770,128 and Bennett, U.S. Pat. No. 3,891,555 probably come closest to applicant's invention in that they teach the use of an air stream to circulate water through a series of filters. They both teach the use of internal filters in series and provide for ready removal and replacement as does applicant. Neither of these, however, teach a circulation system which provides for agitation and removal of solid particles which are known to accumulate and contaminate the bottom of aquariums.